1. Field of the Invention
The invention relates to a power management system and, more specifically, relates to a power management system controlling charge and discharge of storage batteries according to power requirement of loads.
2. Description of Related Art
In electric power management, it is preferable to generate and transmit electric power efficiently according to power consumption of loads. Japanese Patent Application Publication No. 2008-136259 describes a power supply system for a network system. The power supply system includes: multiple solar power generation and supply systems connected to a communication line; and an information source apparatus configured to measure weather information, such as amount of solar radiation, and transmitting the same to the solar power generation and supply systems. With use of the power supply system, load apparatus can be driven efficiently based on highly accurate prediction on the amount of power generation.
If the power consumption of the loads varies, the power consumption can reach excessively high peak power, leading to very high power demand in some cases, and the power supply cannot cover the peak power in some other cases. Storage battery devices can therefore be used to average the supplied and demanded power. The storage battery devices can be secondary batteries such as lithium ion batteries. Japanese Patent Application Publication No. 2006-140094 discloses a lithium ion battery management system which determines which of the charge and discharge states a lithium ion battery is in, based on measurement values of charge/discharge current and temperature of the lithium ion battery and power feeding information of the commercial power supply, and calculates the remaining capacity of the lithium ion battery.